The present development relates to an improved method for propylene production utilizing a classical dehydrogenation catalyst. Specifically, the method combines hydrogen recycle with an extended dehydrogenation reaction cycle resulting in a surprising stabilization of the production rate in an aliphatic hydrocarbon dehydrogenation process.
Dehydrogenation of aliphatic hydrocarbons to produce their complementary olefins is a well-known process. In the typical “Houdry” process, an aliphatic hydrocarbon, such as propane, is passed through a dehydrogenation catalyst bed where the hydrocarbon is dehydrogenated to its complementary olefin, such as propylene, the olefin is flushed from the bed, the catalyst is regenerated and reduced, and the cycle is repeated. (See, for example, U.S. Pat. No. 2,419,997 and incorporated herein by reference.)
Theoretically, the catalyst should return to its original state following the regeneration stage. In practice, however, when the catalyst has been on-stream for some extended period of time, the catalyst—as is known in the art for aged catalysts—demonstrates some loss in functionality and the propylene yield gradually decreases. Thus, it would be advantageous if a method could be developed that would decrease the rate of loss of functionality of the catalyst, thereby increasing the catalyst lifetime and, that preferably would improve the activity and the selectivity of the catalyst, thereby maintaining yield of the desired olefins.